Method of controlling the user calling load in soft switch system

ABSTRACT

The method of controlling the user calling load in Soft Switch system in present invention comprises the steps of: basic calling module receives the congestion direction message; judge whether the system congestion indicated by said congestion direction message is sporadic or sustaining; control the switching of user calling load according to the judgment whether the system congestion indicated by said congestion direction message is sporadic or sustaining. The aggressive effectiveness brought by present invention are: the system has the higher stability and reliability; when the traffic overload state occurs, the setup of maximum calling number can be guaranteed and the system can also restore to the normal load state. Soft module doesn&#39;t influence the setup of normal calling, nor does the setup of urgency special service calling; the system possesses good adaptability, the controlling of load is efficient and stable, and has the self-adapting overload controlling capability.

FIELD OF INVENTION

The present invention relates to a method for service process in anelectronic communication network system, and more particularly to amethod of controlling call load in an IP network with a core soft switchsystem.

BACKGROUND OF THE INVENTION

Nowadays, information is highly centralized, and a telephone switchsystem frequently faces a burst of traffic peak. For example, during acertain period in a holiday or after a regional outburst eventoccurring, a large number of call requests congest local telephonenetworks, and then a calling connection may not be completed for a longtime. Sometimes even the switch needs to reset its system, which notonly interrupts emergency calling connection, but also directly affectsservice quality and equipment maintenance of switch system.

Traffic load is often controlled by a method of sharing traffic load incurrent techniques to promote flow of centralized burst traffic. Butwhen an overflowed route is not idle and its certain calls areoverflowed too, this method is unable to process the overflow traffic.On the contrary, network congestion can be aggravated by the method,when heavy overflow traffic occurs. Thus, this method is obviously notsuitable for current complex and changeful traffic structure.

The same problem described above, namely how to control traffic loadeffectively, is faced in soft switch system that is the core equipmentdeveloping from circuit switching network to packet switching network,an important system in next generation of telecommunication network.

A prior art most related to the present invention is U.S. Pat. No.5,933,481, which discloses “a method of controlling call traffic in atelecommunication system”. The invention provides a method ofdynamically altering the rate at which incoming offered calls areaccepted, including the step of successively determining the offeredcall rate of the incoming offered calls. In this method when the offeredcalls increase, the system accepts the calls at a lower rate. For twogapping intervals used by the invention, the shorter gapping interval isused to accept the calls when the offered call rate is no greater than aset value; the longer gapping interval is used to accept the calls whenthe offered call rate exceeds the set value.

However, there are disadvantages in this method as follows:

A fluctuation can happen when processing burst calls, either acceptingcalls beyond system process capacity, or refusing some calls when systemis able to accept calls. For example, within a short period of time, thesystem offers calls beyond system process capacity, and thensubsequently the system could not offer any calls at all.

In a practical application, the load accepted by a system generallyhappens for a short time, which can't cause system congestion. Thus, allof offered calls can be processed by the system. If too many calls iscontinuously received within a period of time, the system should refuseto process some of the calls, in which, furthermore, the refused callsshould not be emergency calls for special services.

The present invention provides a method of controlling call traffic loadin an IP network to overcome current technical disadvantages.

SUMMARY OF INVENTION

The object of the invention is to provide a method of controlling callload in an IP network with a soft switch system as a core, in which,when mass traffic happens in the soft switch system, the rate ofaccepting calls is adjusted dynamically according to traffic load so asto quickly recover a normal traffic load and avoid congestion andcongestion diffusion phenomena occurred in the soft switch system.

To achieve the above object, the technical solution of the inventionincludes the steps as follows:

A method of controlling call load in a soft switch system, including:receiving a congestion indication message in a basic calling module;deciding whether the system congestion indicated by the congestionindication message is in a type of burst or duration; implementingcontrol for starting call load according to the decision of the burst orduration type for the system congestion.

Preferably, the step of deciding whether the system congestion indicatedby the congestion indication message is in a type of burst or durationis implemented by using timer T1 and T2; the timer T1 is a shorterduration timer; the timer T2 is a longer duration timer.

Preferably, the step of receiving a congestion indication message in abasic calling module further includes as follows: deciding whether ornot it is first time for the basic calling module to receive acongestion indication message; if yes, setting a traffic load status asa lowest level of overload status, and initiating the timer T1 and T2.

Preferably, the step of deciding whether the system congestion indicatedby the congestion indication message is in a type of burst or duration,further includes: deciding whether the timer T1 and T2 is overtime ornot; if the timer T1 is not overtime, implementing a normal call processin the basic calling module; if the timer T1 is overtime but the timerT2 is not overtime, which indicates that the system congestion indicatedby the congestion indication message may be in a type of duration,reinitiating the timer T1 and T2; if the timer T1 is overtime but thetimer T2 is not overtime, and the traffic load status is the highestlevel of overload status, sending a congestion alarm to an operation andmaintenance system (OAM) from the basic calling module; if both thetimer T1 and the timer T2 are overtime, which indicates that the systemcongestion indicated by the congestion indication message is in a typeof burst, reinitiating the timer T2; if both the timer T1 and the timerT2 are overtime and the traffic load status reaches normal status,implementing a normal call process in the basic calling module.

Preferably, the step of implementing control for starting call load,further includes the steps as follows: refusing to accept non-emergencycalls, when the system congestion indicated by congestion indicationmessage is in a type of duration; and dropping the traffic load statusdown one level and decreasing a rate of refusing calls, when the systemcongestion indicated by congestion indication message is in a type ofburst.

Preferably, the step of refusing to accept non-emergency calls, furtherincludes the steps as follows: moving the traffic load status up onelevel; counting a number of call requests received; working out a rateof refusing calls by using a traffic load controlling algorithm;refusing to accept non-emergency calls according to the rate of refusingcalls.

Preferable, the rate of refusing calls is in direct proportion to anumber of calls that should be refused to accept except emergency calls;the rate of refusing calls is in inverse proportion to a number of callsthat is counted subsequently after the current call requests is startedto count; the number of calls that should be refused to accept exceptemergency calls is bigger than or equal to the number of calls that iscounted subsequently after the current call request is started to count.

Preferably, the traffic load control algorithm is calculated inaccordance with a process load of the soft switch system in the IPnetwork, and load of related data bearer network.

Preferably, the process load of the soft switch system is obtainedaccording to the following parameters: a rate of time occupied by CPUinside the soft switch system; traffic of communication for eachsoftware module inside the soft switch system; a average time delay foraccess of database inside the soft switch system; a memory capacityoccupied by the call processing inside the soft switch system, and apercentage of free memory; and a process load percentage and messageforwarding delay of communication process equipments inside the softswitch system.

Preferably, the load of related data bearer network is obtainedaccording to the following parameters: a traffic percentage of each dateport, a communication delay in each router, a communication jitter ineach router, a communication packet lost rate in each router, andadjacent network traffic.

Preferably, the following conditions must be satisfied for controllingthe traffic load by the traffic load control algorithm:

emergency calls is ensured unblocked; calls from important users andpriority users are ensured; calls from normal users are limited by afour level mode, in which call restraint rates are 50%, 75%, 87.5% and100%; when traffic load is caused by a media stream, the soft switchsystem should shunt traffic of related date network, though soft switchitself is not overloaded; when traffic congestion is caused by a mediastream, the coding mode of the media stream is controlled to reducemedia traffic, for example, original G.711 coding mode providing voicequality is changed into G.732 or G.729 mode adopting high compressionrate.

The active effect brought by the present invention is that the systemhas higher stability and reliability. Once traffic overload statusoccurs, connections with the maximum number of calls are ensured, andthe system could be recovered to normal load status quickly. Normal callconnections are not interrupted by soft modules, and connections foremergency calls for special services are not blocked by overloadedtraffic. This method is suitable for wide applications, and its trafficload control is smooth and effective with a adaptive overload controlcapability.

Example embodiments will be described in details below with reference tothe accompanying drawings for further and comprehensive understandingfor the object, characteristics and merits about the present invention.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a flow chart depicting a basic calling module of a soft switchsystem in traffic overload status; and

FIG. 2 is a flow chart depicting a call process of a basic callingmodule.

DETAILED DESCRIPTION OF THE INVENTION

When the call traffic received by the soft switch system has exceededthe traffic load capability that the system can handle, a congestionindication message is sent to a basic calling module. No action is takenfor all congestion indication messages received during timer T1, and itspurpose is to make ensure no quick drop for the system traffic and alsobe able to effectively identify whether the system is overloaded withinduration of very short time.

The present invention will be further described below with reference tothe accompanying drawings.

As shown as FIG. 1, in step 101, it is checked whether or not thecongestion indication message is received by the basic calling modulefor the first time. If yes, change the traffic load status of system andset it as the lowest level (step 102), and also set the two timers, T1with a shorter duration and T2 with a longer duration (step 103).

If no, it is checked whether the timer T1 is overtime and T2 is notovertime (step 104); if yes, the traffic load status of basic callingmodule is moved one level up (step 105), and then it is checked whetherthe traffic load added is beyond the maximum threshold or not (step106); If yes, the timers T1 and T2 is reinitiated (step 107); if no,which is explained that the system still has the congestion indicationmessage although the traffic load status of the basic calling module hasreached to the highest level, send the congestion indication message toOAM (step 108); then end the current service flow, and enter to a statusof waiting message.

If in step 104, the timer T2 is overtime, which is indicated that thecongestion indication message has not been received during a duration ofT2, the traffic load status is dropped one level down, and T2 isreinitiated; if at this time the T2 is overtime again, the traffic loadstatus is dropped one level down again, until the traffic load status isrecovered to a normal status; it is further checked whether neither thetwo timers T1 and T2 are overtime (step 109); if yes, enter directly toa waiting status; if no, the two timers T1 and T2 are reinitiated (step110), and then enter to a waiting status.

As shown as FIG. 2, firstly it is checked whether the basic callingmodule has received a congestion indication message, namely whethercurrently the system has been in a status of traffic overload (step201); if no, process calls normally (step 202); if yes, which isindicated that the system now has been in an overload status, set acurrent traffic load level (step 203), then set the correspondingalgorithm according to the traffic load level (step 204) to work out therate of refusing to accept non-emergency calls. The detail algorithm isas follows: starting from the current call, m calls should be refused toaccept within subsequent n calls, (m<n), in which emergency calls shouldnot be included in the m calls. Therefore, the rate of refusing toaccept calls is:p=m/n

The traffic load levels can be preset according to actual performance ofthe soft switch equipment. In general, p=0, namely no calls need berefused. When the traffic load increases up to the status on whichtraffic load should be controlled, the value of p should be adjust top>0. If at this time the traffic load still increases continuously, pshould be increased continuously. When p=1, it is indicated that allcalls (except emergency calls) are restricted, in this way the systemcould always run in a preset safe range. Then run the step of refusingto accept non-emergency calls (step 205).

Thus, the service flow is ended and the system enters into a status ofwaiting message.

In the present invention, the algorithm for controlling traffic load isworked out according to the process load of the soft switch itself andthe load of related data bearer network.

The process load of the soft switch itself can be obtained according tothe following parameters:

a rate of time occupied by CPU inside the soft switch system;

a traffic of communication for each software module inside the softswitch system;

a average time delay for access of database inside the soft switchsystem;

a memory capacity occupied by the call processing inside the soft switchsystem, and the percentage of free memory; and

a process load percentage and message forwarding delay of communicationprocess equipment inside the soft switch system.

The load of related data bearer network can be obtained according to thefollowing parameters:

a traffic percentage of each date port;

a communication delay in each router;

a communication jitter in each router;

a communication packet lost rate in each router; and

adjacent network traffic.

The following principles should be included for controlling traffic loadby the traffic load control algorithm:

emergency calls (such as 110, 119, 112) should be ensured unblocked;

calls from important users and priority users (such as governmentdepartments, armed forces, and polices) should be ensured; calls fromnormal users are limited by a four level mode, in which call restraintrates are 50%, 75%, 87.5% and 100%;

when traffic load is caused by a media stream (in a soft switch system,the soft switch solely completes call process, while the media streamswitch is completed by data network), the soft switch system shouldshunt traffic of related date network though soft switch itself is notoverloaded; and

when traffic congestion is caused by a media stream, the coding mode ofthe media stream is controlled to reduce media traffic, for example,original G.711 coding mode providing voice quality is changed into G.732or G.729 mode adopting high compression rate.

All above description is only preferable embodiments of the presentinvention, which should not be seen as a limitation for the invention,and the scope of the invention claimed for protection shall not limitedto these description. According to the technologies disclosed by theinvention, any equivalent modifications and variances made by a personskilled in the art should fall into the scope claimed by the invention.

1. A method of controlling call load in soft switch system,characterized by including: receiving a congestion indication message bya basic calling module; deciding whether the system congestion indicatedby the congestion indication message is in a type of burst or duration;and implementing control for starting call load according to thedecision of the burst or duration type for the system congestion.
 2. Themethod as claim 1, characterized by that the step of deciding whetherthe system congestion indicated by the congestion indication message isin a type of burst or duration is implemented by using timer T1 and T2.3. The method as claim 2, characterized by that the timer T1 is ashorter duration timer, and the timer T2 is a longer duration timer. 4.The method as claim 2, characterized by that the step of receiving acongestion indication message in a basic calling module further includesthe steps of: deciding whether or not it is first time for the basiccalling module to receive a congestion indication message; if yes,setting a traffic load status is as a lowest level of overload status,and initiating the timer T1 and T2.
 5. The method as claim 2,characterized by that the step of deciding whether the system congestionindicated by the congestion indication message is in a type of burst orduration, further includes the steps of: deciding whether the timer T1and T2 is overtime or not; if the timer T1 is not overtime, implementinga normal call process in the basic calling module; if the timer T1 isovertime but the timer T2 is not overtime, which indicates that thesystem congestion indicated by the congestion indicating message may bein a type of duration, reinitiating the timers T1 and T2; if the timerT1 is overtime but the timer T2 is not overtime, and the traffic loadstatus is the highest level of overload status, sending a congestionalarm to an operation and maintenance system from the basic callingmodule; if both the timer T1 and the timer T2 are overtime, whichindicates that the system congestion indicated by the congestionindication message is in a type of burst, reinitiating the timer T2; andif both the timer T1 and the timer T2 are overtime, and the traffic loadstatus reaches normal status, implementing a normal call process in thebasic calling module.
 6. The method as claim 1, characterized by thatthe step of implementing control for starting call load, furtherincludes the steps of: refusing to accept non-emergency calls, when thesystem congestion indicated by congestion indicating message is in atype of duration; and dropping the traffic load status down one leveland decreasing a rate of refusing calls, when the system congestionindicated by congestion indication message is in a type of burst.
 7. Themethod as claim 6, characterized by that the step of refusing to acceptnon-emergency calls, further includes the steps of: moving the trafficload status up one level; counting a number of call requests received;working out a rate of refusing calls by using a traffic load controllingalgorithm; and refusing to accept non-emergency calls according to therate of refusing calls.
 8. The method as claim 7, characterized by thatthe rate of refusing calls is in direct proportion to a number of callsthat should be refused to accept except emergency calls.
 9. The methodas claim 7, characterized by that the rate of refusing calls is ininverse proportion to a number of calls that is counted subsequentlyafter the current call requests is started to count.
 10. The method asclaim 8, characterized by that the number of calls that should berefused to accept except emergency calls is bigger than or equal to thenumber of calls that is counted subsequently after the current callrequest is started to count.
 11. The method as claim 7, characterized bythat the traffic load control algorithm is worked out in accordance witha process load of the soft switch system in the IP network, and load ofrelated data bearer network.
 12. The method as claim 11, characterizedby that the process load of the soft switch system is obtained accordingto the following parameters: a rate of time occupied by CPU inside thesoft switch system; a traffic of communication for each software moduleinside the soft switch system; an average time delay for access ofdatabase inside the soft switch system; a memory capacity occupied bythe call processing inside the soft switch system, and a percentage offree memory; and a process load percentage and message forwarding delayof communication process equipments inside the soft switch system. 13.The method as claim 11, characterized by that the load of related databearer network is obtained according to the following parameters: atraffic percentage of each date port, a communication delay in eachrouter, a communication jitter in each router, a communication packetlost rate in each router, and adjacent network traffic.
 14. The methodas claim 7, characterize by that the following conditions must besatisfied for controlling the traffic load by the traffic load controlalgorithm: emergency calls are ensured unblocked; calls from importantusers and priority users are ensured; a four level mode is adopted tolimit calls from normal users, in which call restraint rates are 50%,75%, 87.5% and 100%; when traffic load is caused by a media stream, thesoft switch system should shunt traffic of related date network, thoughsoft switch itself is not overloaded; and when traffic congestion iscaused by a media stream, the coding mode of the media stream iscontrolled to reduce media traffic, for example, original G.711 codingmode providing voice quality is changed into G.732 or G.729 modeadopting high compression rate.
 15. The method as claim 3, characterizedby that the step of receiving a congestion indication message in a basiccalling module further includes the steps of: deciding whether or not itis first time for the basic calling module to receive a congestionindication message; if yes, setting a traffic load status is as a lowestlevel of overload status, and initiating the timer T1 and T2.
 16. Themethod as claim 3, characterized by that the step of deciding whetherthe system congestion indicated by the congestion indication message isin a type of burst or duration, further includes the steps of: decidingwhether the timer T1 and T2 is overtime or not; if the timer T1 is notovertime, implementing a normal call process in the basic callingmodule; if the timer T1 is overtime but the timer T2 is not overtime,which indicates that the system congestion indicated by the congestionindicating message may be in a type of duration, reinitiating the timersT1 and T2; if the timer T1 is overtime but the timer T2 is not overtime,and the traffic load status is the highest level of overload status,sending a congestion alarm to an operation and maintenance system fromthe basic calling module; if both the timer T1 and the timer T2 areovertime, which indicates that the system congestion indicated by thecongestion indication message is in a type of burst, reinitiating thetimer T2; and if both the timer T1 and the timer T2 are overtime, andthe traffic load status reaches normal status, implementing a normalcall process in the basic calling module.
 17. The method as claim 9,characterized by that the number of calls that should be refused toaccept except emergency calls is bigger than or equal to the number ofcalls that is counted subsequently after the current call request isstarted to count.
 18. The method as claim 11, characterize by that thefollowing conditions must be satisfied for controlling the traffic loadby the traffic load control algorithm: emergency calls are ensuredunblocked; calls from important users and priority users are ensured; afour level mode is adopted to limit calls from normal users, in whichcall restraint rates are 50%, 75%, 87.5% and 100%; when traffic load iscaused by a media stream, the soft switch system should shunt traffic ofrelated date network, though soft switch itself is not overloaded; andwhen traffic congestion is caused by a media stream, the coding mode ofthe media stream is controlled to reduce media traffic, for example,original G.711 coding mode providing voice quality is changed into G.732or G.729 mode adopting high compression rate.